U.S. Pat. No. 3,813,185 shows a structure for rotor blades in a turbo machine (e.g., a gas turbine engine) comprising a substantially cylindrical or a conical hollow drum of fibrous material and a plurality of metal blade carrier bars, attached side by side on each side of the blades. The art techniques revealed in that patent are representative of state-of-the-art applications of composite manufacturing techniques, as applied to gas turbine engine rotors. Other rotor techniques used in the prior art consist of entirely metallic or alloy rotors with machined slots that receive the rotor blades.
Some lightweight compressor rotor designs utilize an integrally-bladed Ti MMC drum. It is a common goal to use compressor airfoils that are integral with the rotor itself. When a Ti MMC drum is employed, the integral airfoils are made of a Ti alloy similar to that of the drum matrix material, which permits metallurgical joining of the two. While this arrangement allows for high rim speed capabilities, maximum discharge temperatures are limited to the 1400 to 1500 F. range due to the capability of available materials.